How to Make high quality Gold Bar & Bullion -Vacuum gold bar casting machine

How to Make high quality Gold Bar & Bullion -Vacuum gold bar casting machine


Gold is a permanent substance, and its value has been recognized internationally, so it has played an important economic role since ancient times! As we all know, the most important value of investing in gold lies in the “eternal value” that will not evaporate from the world and will never disappear. In the current world of ultra-long-cycle inflation, for most ordinary investors, investing in gold is undoubtedly better than stocks. Safer and the best way to resist risks.


Investing in gold bullion has become the best choice for many investors. From an investment perspective, investing in gold bullion is based on international gold prices with a small amount of handling fees. The most important thing is to withdraw physical objects to reduce investment risks. With the strong gold bull market Trend, win in stability.

There are currently two main ways to make gold bars in the market, the traditional gold bar casting method and the vacuum gold bar casting method.

Traditional gold bar casting method:

The traditional casting method is usually suitable for mines. The gold is smelted into liquid at high temperature, and appropriate flux  is added during the smelting process. The flux is used to purify the gold, and then pour the molten gold liquid  into the customized mold, so that you can get different specifications of gold bars. After the gold bars are fully cooled, we can use the hydraulic press to mark the gold bars with our own logo, so It can be sold on the market.The gold bar casting by this method do not have the shinning surface as the bars comes from the vacuum casting methods

make gold bar
Vacuum gold bar casting method:

The vacuum casting method is usually the most commonly casting method for gold bars in refineries., first we should put the purified high purity gold powder in the metal granulator to make a uniform size gold grains , and then we weight these gold gains and placed into the graphite mould according to the required bar bar weight.

The whole melting & casting will be under vacuum condition and argon protection, so that the surface of the gold bars made bright as a mirror, no water ripples, very popular with investors.

The last thing you need to do is to use a small hydraulic press to apply your company’s logo and  patters to the surface shiny gold bars, which are very popular among investors.

Now let us talk in details about the Traditional gold bar casting method:

Even though some customers  still resort to gas-fired melting, gold  medium-frequency induction furnaces are currently the most widely used and popular method of melting gold because of the rapid melting speed and operation is more convenient for the users

CDOCAST Integrated gold melting machine is the most popular in the market, now let us introduce this furnace.

Melting capacity: 1-15kg per batch

Crucibles: pure graphite crucible comes with the quartz crucible as protect

Melting temperature: 1650 C

Melting time : 3-5 mins

Water cooling: comes with the water pump inside of the machine.

This small integrated gold melting machine adopt the most advanced induction technology.Usually the gold bars on the market are mostly 1kg-5kg, so the 10kg gold melting furnace is the best-selling. It only takes about 5 minutes to fully melt 10Kg. Calculated based on a kilogram of graphite mold, one furnace at a time, You can make 10 gold bars, and the production efficiency is very high.

The  overall size of this metal melting machine is about 600mm*500mm*1000mm, and the weight is about 70kg. The bottom of each machine is equipped with dual-purpose rollers. The machine can be fixed on the ground or slide with the rollers. due to its small size.and light weight, the transportation cost of this gold melting machine  is  greatly saved. For customers who do not have enough space in the workshop, this gold melting machine is the best choice.

Graphite mould:

CDOCAST  Can customized the graphite mould according to client requirement, usually we have the sizes from capacity 50g to 5000g, our graphite comes with the stainless steel hand which is fixed to the graphite mould, in this way, after the gold bar is cooled down,  can be take out more easily

crucible of gold melting machine

Vacuum  gold bar casting machine

Vacuum gold  bar casting machine, as the name implies, the entire melting and casting process is carried out under  a vacuum environment, and  is  flushed with inert  protective gas, so as to minimize the oxidation of the gold or silver bullion and  obtain the highest quality  bars. due  to the protection of the vacuum environment, The loss of precious  is also  the least among all  bars casting  method.

Vacuum induction melting furnace

Graphite moulds can be customized according to the different requirement of customers, which the size  can be 50g, 1oz, 10oz, 100oz etc. We can customize graphite molds for customers according to the specifications of gold bars provided by customers, so that customers can cast the desired gold bars.

This gold vacuum casting machine adopts induction heating technology which  greatly   improve the production efficiency. The basic melting time is about 7 minutes, and the cooling time is also 7 minutes. The whole casting process can be completed within 15 minutes, and it can continuely  working  for 24 hours.

For the model cdo-4, which can cast 4 pcs 1kg bars one time, means you can cast about 16 pcs 1kg gold bar in one hour.

Water cooling is a very important factor that determines whether  the  vacuum gold & silver bullion casting machine can operate  normally or not. CDOCAST also provides you with industrial water  chillers that match the vacuum bar casting machine. We recommended our air-cooled water chillers because of their smaller size which is  easy to transport,  what is more, this water chiller can provide sufficient cooling capacity , and the connection  to our vacuum casting machine is  simple. Our air-cooled  water chiller  is designed with multiple over-current and over-temperature alarm systems. When the water temperature exceeds the required range of the machine, the water cooler will automatically alarm. Therefore, we recommend you One-stop purchase from us.

Next, let’s take a look at the specific process of how to make high-quality mirror-finished gold bars or silver bars.

Step 1: Make the gold or silver grainsgold granule

The  metal granulator  refers to the equipment  that can make gold or silver into particles of uniform size. The working principle of the granulator is to adopt the intermediate frequency induction heating to melt the precious metals that need to be pelletized to quickly dissolve,  the bottom of the molten graphite crucible is drilled with  many small holes . The smelted  metal flows into the water tank through these small holes,  so that gold particles of the same size and specifications are made. CDOCAST granulator also designed with argon protection device, for some easily oxidized metals, inert gas protection can protect precious metals from oxidation.]

After obtaining the desired gold or silver grains, you can conveniently weigh them and put them into the graphite mould of the vacuum casting machine. (If you put a large piece of gold or silver block, due to thermal expansion and contraction, the expanded gold nugget will easily squeeze out the cracks of the graphite mould and damage the mould)

Step2Vacuum gold & silver bar casting machinegold bar

Put the weighed gold or silver grains into the graphite mold, and we can start  the process to  cast the gold or silver bars. First, use thecustomized graphite clip to put the graphite mold with the gold particles into the cooling plate, the cooling  plate is designed to be square  And same  size and shape of the graphite mold, and the cooling plate can automatically rise and fall. After the graphite mold is well placed, the cooling plate will automatically drop to the position of the induction coil and ready to melt, At this time, we have to close the furnace door and vacuumize the full melting  chamber  to prepare for melting and casting.

The entire smelting is carried out in a high vacuum environment, The entire melting process  is carried out in a high vacuum environment, and the advanced induction  heating technology allows the entire smelting process to be completely in about 6 minutes. During This melting process does not require manual operation which  can save labour for users. After the smelting is completed, it  will automatically  rush into the inert gas protection and cool down. Considering the  graphite is easily oxidized in high temperature  when contact with air, it will greatly reduce the life of the graphite mold. Therefore, the entire cooling process is also carried out in a vacuum environment, which can greatly improve the life of the graphite mold.

After 7 minutes of cooling, the gold bars will be completely formed and shaped , finally you will  get a shiny gold bar without ripples.

Step 3:Stamping logos on the gold barsgold bar

CDOCASTFour column hydraulic press  is specially designed to print logos and patterns on gold bars. The four-column hydraulic press is a kind of special hydraulic oil as the working medium and the hydraulic pump as the power source. The hydraulic oil enters the cylinder/piston through the hydraulic pipeline by the force of the pump, and then there are several sets of mutually matched seals in the cylinder/piston The seals at different positions are different, but they all play a sealing role to prevent hydraulic oil from leaking. Converting hydraulic energy into mechanical energy Hydraulic transmission is a transmission method that uses hydraulic pressure to transmit power and control. The hydraulic device is composed of hydraulic pump, hydraulic cylinder, hydraulic control valve and hydraulic auxiliary components.

In addition to providing hydraulic presses, we also have a professional team that can design 3D drawings  for the die and the tools for the dies.


1.The four-column structure is simple, economical and practical; the frame structure has good rigidity, high precision and strong anti-fraud load ability.

2.The hydraulic control adopts an integral cartridge valve set system, which reduces leakage points, reliable action and long service life.

3.The electrical system controlled by PLC which is compact, sensitive, reliable, and flexible.(PLC control system is optional purchase)

4.The working pressure and stroke can be adjusted within the specified range according to the process requirements, and the operation is simple.

Step 4: Dot peen number marking machine to mark serial numbersgold bar number

Pneumatic marking machine is a computer-controlled printing needle that moves in a certain trajectory in the X and Y two-dimensional planes, while the printing needle makes high-frequency impact motion under the action of compressed air, thereby printing a certain depth of mark on the workpiece. Main features of pneumatic marking machine: It has a large depth, direct marking output through the computer, and the marking is neat and clear; the main typical applications: automobile and motorcycle parts, instruments, machinery, automobiles, signs and other industries.

By inputting the content of serial number to be printed into the computer, the computer marking software converts the content  into digital control signals, transmits them to the controller, and drives the printing to print characters and graphics composed of continuous dot matrix on the workpiece; the needle is at X -Y two-dimensional plane moves according to the set trajectory, and the printing needle prints a concave mark composed of dense dot matrix on the surface of the workpiece under the action of compressed air.

The advantage of pneumatic marking machine is to realize online printing on higher hardness metals through dot matrix